Kid Niki: Radical Ninja, known in Japan as Kaiketsu
Yanchamaru(快傑ヤンチャ丸,Kaiketsu
Yanchamaru?
lit. "The Wonderful Yanchamaru"), is an arcade game
developed and published by Irem in 1986, and was later published outside of Japan by
Data East in 1987. The arcade game runs on
Irem-62 Hardware, the same as Kung-Fu Master. The differences between the
Kid Niki: Radical Ninja and Kaiketsu Yancha Maru are minimal. Aside
from text translation, the most glaring difference is the main
character's hair style. Kid Niki's hair is more "punk rock" with
wild spikes and a ponytail in the back. Yancha Maru's hair has more
subdued spikes and a topknot (or chonmage). In the arcade version
of the game, the main character's keikogi is yellow while it is red
in the home ports.

Kid Niki is armed with the Spinning Sword, which according to
the game's manual, "has been passed down from generation to
generation from the School of Chirin." In addition to the spinning
sword, Kid Niki can gain extra offensive power by collecting Bells.
The Golden Bell allows him to launch a projectile every time Kid
Niki spins his sword, and the Silver Bell creates a spinning force
field around him. Both of these power-ups last for a limited amount
of time. The game is divided up into seven rounds, with a boss
character at the end of each one.

In 1987, Data East released ports of the game for the
NES,
Commodore 64, and Apple II. Curiously, all home
versions of the game show screen shots from the graphically
superior arcade version on the back of their packages. Although it
is an Irem game, the home ports were one of the more successful
games released by Data East. In Japan, two sequels appeared
for the Famicom. The first was Kaiketsu
Yanchamaru 2: Karakuri Land in 1991, and the second was
Kaiketsu Yanchamaru
3 in 1993. Each of the three NES/Famicom titles feature
radically different character designs. There was also a Game Boy
sequel called Ganso!!
Yanchamaru in 1991. This portable sequel is a unique game
and not a port of one of the existing Kid Niki/Yanchamaru titles.
Kid Niki makes a cameo appearance in Irem's NES game, Kickle
Cubicle.

One day in Feudal Japan, Kid Niki, the most radical of ninjas,
is training at his Ninja School. Suddenly, a passing bird is struck
down by an arrow and lands at Niki's feet. Attached is a note
explaining that Niki's girlfriend, Princess Margo, has been
kidnapped by the evil Stone Wizard. With the cry of "Will help
you!" Niki bursts through the wall of his school and sets off on
his quest to save Margo.